The present invention relates to a process of the catalytic decomposition of chlorofluoro-alkanes commonly named as "flons". More particularly this invention relates to the process of decomposing chlorofluoro-alkanes by using the catalyst to non-hazard compounds in the presence of steam.
Chlorofluoro-alkanes, wherein the hydrogens of hydrocarbon are wholly or partially substituted with fluorine and chlorine, (hereinafter may be abbreviated as flons) are stable both in chemical and thermal properties, non-toxic and has no smell. For that reason, they have been widely used as most safe substances for refrigerant, foaming agent, solvent and so on.
However, recently among these flons, particularly chlorofluorocarbons (CFC), wherein all of the hydrogen atoms are substituted with fluorine and chlorine, have been found to be decomposed in the ozone layer of the stratosphere and to have high possibility of destructing the ozone layer. It has been determined that the production of such flons should be gradually reduced by substituting the one which does not destruct the ozone layer for them.
Accordingly, in addition to the development of such substitute, the development of the process of decomposing the presently used flons into the substances which are no fear of destructing the ozone layer before giving off the flons into air has been desired.
However, such flons are extremely stable compounds, poor in the reactivity and are considered to be difficult to act on the decomposition reaction. Plasma method of decomposition at very high temperature and so on are known, but presently a few of the reports concerning the study of catalytic decomposition reaction have been published.
However, as a method of treating the exhausted gases such a large scaled and high cost method as plasma method is difficult in practical applications so it is almost impossible to really use it for the solution of ozone problem. In order to be easily applicable in the place where they want for users of flons and prevent environmental pollution, the best method is simply to decompose flons by means of catalyst. Accordingly the object of this invention is to provide the decomposing method into harmless substances without hazard of destructing the ozone layer in using or after using flons before giving off into air.
Flons are hydrolyzed and decomposed to form hydrogen chloride, hydrogen fluoride and carbon dioxide gas, and can be collected all as harmless compounds by neutralizing hydrogen chloride and hydrogen fluoride. As the result of our researches to find the catalyst decomposing such flons, we, this inventors, have eventually found that the catalyst comprising iron oxide supported on active carbon can decompose flons extremely effectively and can convert into harmless compounds against ozone destruction and have reached this invention.